Another option you may consider, if you have an occupied unit in great shape, offer the resident a discount to downgrade.

Buy a property at a big discount from a seller who NEEDS to sell quickly, put it right back on the market after you close at a price where you will sell it fast. 

They buy materials in bulk at substantial discounts and are buying big ticket items like hvac systems wholesale, not at big box retail stores.

Do you mind sharing a few of your strategies of what has been working to find steeply discounted deals in your area? 

Depending on the brokerage there are monthly fees but there are also discount brokerages that charge minimal fees to keep your license active but don't usually offer very much training.

I've got a solid ARV on the property and want to present the seller with a multiple option letter of intent 1) an all cash offer (deep discount) and 2) one on terms; small down payment with the balance payed back over time.

We purchased our first property with cash under an LLC at a discount (~20%).

I highly recommend you bring your utilization down from 4% and work your way down to 2.5% (make sure your payment is submitted 2 days before your credit card company's statement date).I've seen 680s jump to 750 within 3 months.If you have debt it is best to hire an attorney to deal with it or fight the debt yourself and require a written email stating they will remove the inquiry from your credit report after you have paid X% of the debt you owe (you can usually settle for a huge discount).

Maybe ask for discount on commission fee or even hiring him on as a consultant at an hourly rate?

They have vendors that may provide them a discount.